You can go with white sectional sofa with very low Back, very sleek rest arms will make the room appear bigger. Also the TV go for LED or plasma mounting on wall so the space will be saved. If you can have pot lights LED with dimmers will make the room look totally different.

I've attached a great window treatment idea for the bank of windows. A sectional would give maximum seating with a side chair for conversation. Get a highboy for under the TV. There shouldn't be much distance between TV and the furniture piece. This is assuming you don't wish to have a built in cabinetry with a wall mount fireplace below...oooh! Get a significant coffee table with either a shag rug for texture or a rug of many colors to anchor the space. Don't forget task lighting with lamps. Stay away from touchiers.